1

Evidence For Clinical and Research Walking

Activity Measurement in Cerebral Palsy with

the StepWatch (SW)

Kristie F. Bjornson, PT, PhD, MSAssociate Professor Pediatrics

Seattle Children’s Research Institute

University of Washington

Kristie.bjornson@seattlechildrens.org

AACPDM 2018

FINANCIAL DISCLOSURE

AACPDM 72nd Annual Meeting

October 9-13, 2018

Speaker Name: Kristie Bjornson, PT, PhD, MS

1. Disclosure of Relevant Financial Relationships

Grant/Research support from:

F31NS48740-NINDS

SCH Dept of Orthopedic Surgery

SCRI Academic Enrichment Fund

K23HD060764 - NICHD

R21 HD077186- NICHD/NCMRR

2. Disclosure of Off-Label and/or investigative uses:

I will not discuss off label use and/or investigational use in my presentation.

Objectives:

� Understand validity & accuracy of the SW strides taken in typically developing children/youth (TDCY) & with CP.

� Understand the walking activity levels and intensity of TDCY & with CP.

� Examine evidence for SW monitoring duration by Gross Motor Function Level (GMFCS) in children/youth with CP.

� Exemplars- clinical & research SW application in children with CP.

2

Physical

Activity

Walking Activity

When we are not looking3

how and how much are they walking?

Terminology:

� Walking Activity (WA) – step or stride taken for mobility, depending on device may be “step” or stride

� Step - counts both left and right steps

� Stride – step of one leg/side-3DG lab

3

ICF model: WHO 2001

Health Condition

Body Functions & Structures

Activities Participation

Environmental Factors Personal Factors

International Classification of Functioning, Disability & Health. 2001; WHO

Walking Activity Measurement

“Level of Ability” versus “Level of Activity”

Capacity Performance

Relationship of Stride Activity to Mobility-

based Life Habits in Children with Cerebral

Palsy (Bjornson, 2013)

� Average total strides/day was positively associated with the Personal Care, Housing, Mobility, and Recreation Life-H categories.

� Moderate/High walking stride rates (Ave > 30 stride/min/day) was associated with all categories

� Walking activity performance is significantly associated with levels of participation in mobility-based life habits for ambulatory children with CP.

4

Why the StepWatch?

Left hip

Right hip

ActiGraph: child with Spastic Diplegia

Stott, MacKey, 2011

5

Pediatric StepWatch Accuracy/Precision

& comparison to Pedometers:

� Mitre et al (2009)-treadmill trial� Lean and obese children

� Omron and Digiwalker pedometers undercounting compared to manual counts (worse at slower speeds)

� StepWatch had negligible error to manual counts of steps taken

StepWatch Accuracy to Observed

Strides: TDY

� 20 normally developing children

� Age groups

� 5-7 years & 9-11 years

� 3- Two week intervals: 2 months apart

� Comparison manual counts

� Walking 96-97%

� Running 99%

Song K. J Peds Ortho, 26: 245-249;2006

6

StepWatch� Two dimensional accelerometer

� Detects foot leaving the surface

� Completely sealed

� Worn with strap or ankle cuff

� Continuously records steps/time interval

� Up to two months duration

� AKA “SAM”, “StepWatch3” and “GAM”

� www.modushealth.com

NEW UPDATE 2018

StepWatch 4 (SW4)-Activity Monitor� $400 ea with iPad app

� App $1300 1x

� Additional $ monthly cloud-based

� rechargeable

� SW4 available 2018

support@modushealth.com

Seattle Clinical/Research

SW Monitoring Guidelines

� Individually Set:

� Sensitivity

� Cadence

� Pre/Post intervention

� Wearing 7 to 14 days

� Analyze 5 to 14 days

� Depends on clinical question

7

StepWatch: How many days

monitored

� TDY (n= 428, ages 2- 13 yrs) (Kang 2014)

� Need to monitor ave 4.14 days

� (range 3 to 6 by days 2 year age bands)

� Children with CP: (n=209) (Ishikawa, 2013)

� GMFCS:

� Level I 6 days

� Level II 5 days

� Level III 4 days

Kang et al Phys Meas. 2014

Ishikawa et al APRM. 2013

What do we know about walking

with SW in TDY?

Measurement of Walking Activity throughout Childhood: Influence of Leg Length

Bjornson et al, Ped Ex Sci 2010

8

Sample:

� 428 TDY children

� ages 2 to 15 years

� 30 boys / 30 girls per age group

� 7 groups of 2 year increments

� Calibration Accuracy: ave 100%

� (range 90-112, sd 4.0)

Age Group

(yrs) Gender (n)

Average

Stride/Day

60-min

peak 20-min peak 1-min peak

2-3 Boys (30) 8,159 (2,677) 28 (8) 40 (8) 70 (7)

Girls (30) 7,837 (1,771) 28 (5) 39 (7) 73 (10)

Total (60) 7,998 (2,257) 28 (7) 39 (8) 72 (7)

4-5 Boys (31) 9,411 (3,214) 30 (8) 44 (10) 71 (6)

Girls (31) 8,726 (1,992) 29 (6) 41 (8) 71 (7)

Total (62) 9,069 (2,674) 29 (7) 42 (9) 71 (7)

6-7 Boys (32) 9,880 (3,067) 31 (7) 43 (7) 68 (7)

Girls (30) 9,083 (2,492) 29 (5) 42 (6) 70 (6)

Total (62) 9,794 (2,810) 30 (6) 43 (6) 69 (7)

14-15 yr12-13 yr10-11 yr8-9 yr6-7 yr4-5 yr2-3 yr

Age

20000

15000

10000

5000

Avera

ge s

trid

e/d

ay

384

391

270

287

222

150

151

73

109

129

9

14-15 yr12-13 yr10-11 yr8-9 yr6-7 yr4-5 yr2-3 yr

Age group

20000

15000

10000

5000

Ad

juste

d f

or

leg

len

gth

avera

ge s

trid

e/d

ay

384

277

270222

151

73

82

129

150

Basis for Pediatric Walking Intensity

Cut-points for StepWatch (SW)� Intense walking adult US population documented peak

step/min rate of 101 (Tudor-Locke, 2012)

� Intense walking bursts for children (< 18 years of age) are

documented at 108 to 146 peak steps/min rates (10-12).(Barreira, 2012, Bjornson 2010, Tudorlocke, 2002)

� moderate to vigorous physical activity (MVPA) = 120 step/min -10 to 14 y/o boys and girls with another pedometer (Graser, 2011)

� “High” intensity walking for StepWatch > 60 stride/min- as it counts only one leg.

14-15 yr12-13 yr10-11 yr8-9 yr6-7 yr4-5 yr2-3 yr

Age group

100

80

60

40

20

Maxim

al 1 m

inu

te s

trid

es

371

410

353

275

272

209

213

178

7

268

130

10

Walking activity with StepWatch

in children with CP?

Neuromuscular TDY

Scoliosis (VEPTR)

11

Ambulatory Physical Activity Performance in Youth

with Cerebral Palsy & Youth Developing Typically Bjornson Physical Therapy 87(3), 2007

CP (n=81)

TDY (n=30) p

Average step/day

4,222 6,739 .000

% All Time Active

40.2 49.6 .000

Ratio Medium to low Activity

.33 .47 .000

% Time High Activity

5.6 9.7 .000

TDYGMFCS level IGMFCS level IIGMFCS level III

Activity Capacity Functional Categories

12000

10000

8000

6000

4000

2000

0

Av

era

ge

Da

ily

To

tal S

tep

co

un

t/s

tep

Wa

tch

42

TDY to levels I, II & III p <.001, TDY to level I p=.o4,Level I to II p=.09,Level I to III p<.001, level III to II p <.001.

• Compared walking with StepWatch• 5 days of monitoring• 209 youth with CP• 368 TDY• Ages 2-13 years

• Intensity:• Low 1- 30 stride/min• Moderate 31-60 stride/min• High > 60 stride/min

12

39923856

533

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Low (1-30) Mod (31-60) High > 60

TDY

GMFCS level I

GMFCS level II

GMFCS III

39923856

533

3436

2599

262

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Low (1-30) Mod (31-60) High > 60

TDY

GMFCS level I

GMFCS level II

GMFCS III

39923856

533

3436

2599

262

2977

2004

213

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Low (1-30) Mod (31-60) High > 60

TDY

GMFCS level I

GMFCS level II

GMFCS III

13

39923856

533

3436

2599

262

2977

2004

213

1347

433

360

500

1000

1500

2000

2500

3000

3500

4000

4500

Low (1-30) Mod (31-60) High > 60

TDY

GMFCS level I

GMFCS level II

GMFCS III

Clinical/Research Exemplars:

StepWatch Measurement:

� Longitudinal monitoring-

� Scoliosis

� Diplegia (multiple interventions)

� Treadmill training

� Orthotics

� SW combined with GPS-

community mobility

Neuromuscular Scoliosis (VEPTR):

Average Steps/Day

0

1000

2000

3000

4000

5000

6000

Pre A

PR 03

Post D

ec 03

Post A

pr 05

Post F

eb 07

14

0

1000

2000

3000

4000

5000

6000

7000

Nov-99 Btx 3/00 Bac Btx

streng

8/00

3/01

Without

AFO's

Pre Sx

8/01

post sx

4/02

F/U

10/04

Average steps/day: CP Spastic diplegia 8 y/o -GMFCS II

0102030405060708090

100

Base

line 11/

99

Bot

ox 3/0

0

BA

C B

TX

Str

eng

8/00

Withou

t AFO

's 3

/01

Pre

card

iac/

orth

o Sx

Pos

tsx 4

/02

F/U

10/0

4

Low

Med

High

Walking intensity: CP-GMFCS II

Short-burst interval treadmill training walking capacity &performance in cerebral palsy: a pilot study

Bjornson, et al Dev Neurorehab 2018Funding:

R21 HD077186- NICHD/NCMRR

15

Average Strides/day at baseline, post

SBLTT and 6 weeks post SBLTT (n=12).

Walking

Performance

(n= 12, PRE/POST SBLTT)

BL Mean

(SD)

Post 1

Mean

chang

e

p

value

Post 2

Mean

Chang

e

p

value

Average Total

Steps/day

2677

(1060)

+1712 <.001 +948 <.00

1

Percent Time

walking

37.1 (9.5) +7.68 .006 +4.89 .55

Percent Time > 30

steps/min(Mod/Hig

h)

8.37 (4.0) +4.4 .04 +3.8 .04

# Step >30

steps/min

8245 (442) +991 <.001 +627 <.00

1

Peak Activity Index

(ave top 30 one

min)

33.9 (5.4) +9.4 <.001 +6.1 <.00

1

Max # steps 60

mins

13.2 (4.2) +5.8 .006 +4.2 <.00

1

Max # steps 20 22.9 (4.3) +7.3 <.001 +7.1 <.00

Percent of total strides/day in low,

moderate& high stride rates: 368 TDY, 209

youth with CP ,12 youth with CP, Pre/ Post

short-burst LTT.

16

Orthotic Intervention: Walking

Activity with StepWatch

�

SW Orthotics: n= 8 diplegia

4 y/o, spastic diplegia CP:

Average # of Strides/day- low, mod & high

4029 3862

742

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Low (1-30) Mod (31-60) High > 60

TDY (n=62, 4-5y/o)

Avera

ge S

trides/

day

17

4 y/o, spastic diplegia CP:

Average # of Strides/day- low, mod & high

40293862

742

2807

2175

114

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Low (1-30) Mod (31-60) High > 60

TDY (n=62, 4-5y/o)

4 y/o, AFO- OFF

Avera

ge S

trides/

day

4 y/o, spastic diplegia CP:

Average # of Strides/day- low, mod & high

40293862

742

2807

2175

114

3755

3359

492

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Low (1-30) Mod (31-60) High > 60

TDY (n=62, 4-5y/o)4 y/o, AFO- OFF

4 y/o, AFO- ON

Avera

ge S

trides/

day

What are they really doing?Community Walking Activity in Cerebral Palsy: StepWatch &

Global Positioning System (GPS)

Bjornson KF, Hurvitz P, Kerfeld C. (2015) Funding:

SCRI CHBD Stimulus Fund 2013NIH R21 HD077186

18

Stride count intensity home/community

(low, med, high), pre/post Interval

Treadmill training (n=1)

Percent walking time-home/community,

pre/post Interval Treadmill Training (n=12).

19

StepWatch -Take Home

� Highest accuracy to strides taken

of current devices

� Published normative data for TDCY

� Emerging data for children with CP

� Evidence- Monitoring duration

� GMFCS level

I = 6 days; II = 5 days; III = 4 days

� Pediatric cut points for intensity analysis

Potential SW Clinical/Research

Applications

� PRE/POST

� New assistive device/orthotics

� Botox L/E/serial casting

� Ortho surgery- SEML and Spinal

� SDR

� Oral medication movement disorders

� Dose change of ITB pump

� Burst of therapy (OT/PT)

QUESTIONS ?

20

References: Bjornson KF, Zhou C, Stevenson RD, Christakis D. Relation of stride activity and participation in

mobility-based life habits among children with cerebral palsy. Arch Phys Med Rehabil. 2014 Feb;95(2):360-8.

Bjornson KF, Zhou C, Stevenson R, Christakis D, Song K. Walking activity patterns in youth with

cerebral palsy and youth developing typically. Disabil Rehabil. 2014;36(15):1279-84.

Bjornson KF, Belza B, Kartin D, Logsdon R, McLaughlin J, Thompson EA. The relationship of

physical activity to health status and quality of life in cerebral palsy. Pediatr Phys Ther. 2008 Fall;20(3):247-53

Bjornson K, Song K, Lisle J, Robinson S, Killien E, Barrett T, et al. Measurement of walking activity throughout childhood: influence of leg length. Pediatric exercise science. 2010;22(4):581-95.

Bjornson, Lennon Walking and Physical Activity Monitoring in Children with Cerebral Palsy;

Springer International Publishing AG 2017B. Müller, S.I. Wolf (eds.), Handbook of Human Motion,

Bjornson KF, Moreau N, Bodkin A. (2018) Short-burst interval treadmill training walking capacity

and performance in cerebral palsy: a pilot study. Dev Neurorehabil. 2018 Apr 16:1-8

Ishikawa S, Kang M, Bjornson KF, Song K. Reliably Measuring Ambulatory Activity Levels of Children and Adolescents With Cerebral Palsy. Archives of Physical Medicine and Rehabilitation.

2013;94(1):132-7.

Kang M. Bjornson KF BT, Ragan BG, Song K. The minimum number of days required to establish

reliable physical activity estimates in children aged 2–15 years. Physiological Measurement. 2014;35(11):2229

Treacy D. et al. Validity of Different Activity Monitors to Count Steps in an Inpatient Rehabilitation

Setting Phys Ther. 2017 May 1;97(5):581-588.

Toth, LP et al.. Med Sci Sports Exerc 2018StepWatch was the Most Accurate in Real World

Walking